<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        .top {
            /* 宽度高度背景色 */
            height: 40px;
            background-color: #333;
        }
        .header {
            width: 1226px;
            height: 100px;
            background-color: #ffc0cb;
            /* 外边距 */
            margin: 0 auto;
        }
        .content {  
            width: 1226px;
            height: 460px;
            background-color: green;
            margin: 0 auto;
        }
        .left {
            width: 234px;
            height: 460px;
            background-color: #ffa500;
            float: left;
        }
        .right {
            width: 992px;
            height: 460px;
            background-color: #87ceeb;
            float: left;
        }

        /* CSS书写顺序：浏览器执行效率更高
            1、浮动 / display
            2、盒子模型：margin border padding 宽度高度背景色
            3、文字的样式
        */
    </style>
</head>
<body>
    <!-- 通栏的盒子：宽度和浏览器宽度一样大 -->
    <div class="top"></div>
    <div class="header">头部</div>

    <div class="content">
        <div class="left">left</div>
        <div class="right">right</div>
    </div>
    
</body>
</html>